// Licensed to the .NET Foundation under one or more agreements.
// The .NET Foundation licenses this file to you under the MIT license.
// See the LICENSE file in the project root for more information.

using System;
using CommunityToolkit.HighPerformance.Helpers;
using Microsoft.VisualStudio.TestTools.UnitTesting;
using CommunityToolkit.HighPerformance.UnitTests.Buffers.Internals;

namespace CommunityToolkit.HighPerformance.UnitTests.Helpers;

public partial class Test_ParallelHelper
{
    [TestMethod]
    public void Test_ParallelHelper_ForEach_Ref()
    {
        foreach (int count in TestForCounts)
        {
            using UnmanagedSpanOwner<int> data = CreateRandomData(count);
            using UnmanagedSpanOwner<int> copy = new(count);

            data.GetSpan().CopyTo(copy.GetSpan());

            foreach (ref int n in copy.GetSpan())
            {
                n = unchecked(n * 397);
            }

            ParallelHelper.ForEach(data.Memory, new Multiplier(397));

            Span<int> dataSpan = data.GetSpan();
            Span<int> copySpan = copy.GetSpan();

            for (int i = 0; i < data.Length; i++)
            {
                if (dataSpan[i] != copySpan[i])
                {
                    Assert.Fail($"Item #{i} was not a match, was {dataSpan[i]} instead of {copySpan[i]}");
                }
            }
        }
    }

    /// <summary>
    /// A type implementing <see cref="IRefAction{T}"/> to multiply array elements.
    /// </summary>
    private readonly struct Multiplier : IRefAction<int>
    {
        private readonly int factor;

        public Multiplier(int factor) => this.factor = factor;

        /// <inheritdoc/>
        public void Invoke(ref int i) => i = unchecked(i * this.factor);
    }
}
